Konno Procedure for Managing Small Aortic Root during Aortic Valve Replacement Surgery: An Experience of 12 Cases

Background: Small aortic annulus during aortic valve replacement can lead to implanting a smaller sized valve compared to the body surface area thereby causing patient prosthesis mismatch. Various aortic root enlargement techniques have been described depending on anterior or posterior approach. Konno procedure uses anterior approach for aortic root enlargement. In this study, we reviewed results of Konno procedure done from 2011 to 2019 by a single surgeon. Methods: 12 adult patients who underwent aortic valve replacement along with Konno procedure for small aortic root by a single surgeon at a single center between 2011 and 2019 were reviewed. Echocardiographic and demographic data and post-operative data were obtained from medical records. Symptomatic profile was assessed as per New York Heart Association Classification. Intraoperative findings and post-operative period findings were noted. Follow up symptom profile was assessed for these patients. Results: 12 patients underwent Konno procedure between 2011 and 2019 for small aortic root along with valve replacement. The main indication for surgery was aortic stenosis with small aortic annulus, with or without involvement of the mitral valve. Preoperatively, 3 patients had NYHA class II and 9 patients had NYHA class III symptoms. Mean age at operation was 26.42 years, minimum age 10 years, and maximum age 39 years. 3 were females and 9 were males. Mean bypass time was 106.4 low up in the outpatient department suggested all patients had NYHA class I symptoms and anticoagulation with warfarin adjusted to prothrombin time— International normalised ratio. Conclusion: Konno procedure is effective for managing small aortic root as bigger outflow orifice area through the larger valve prosthesis improves ventricular outflow and hence, improves the outcomes.


Introduction
Small aortic root and small aortic annulus are often encountered while performing aortic valve replacement. Implanting a smaller sized valve compared to body surface area increases the risk of patient prosthesis mismatch [1]. In previous studies, patient-prosthesis mismatch has been demonstrated to increase left ventricular (LV) work, to reduce LV mass regression, and hence produce symptoms of aortic stenosis [2]. Approach remains controversial, strategies such as aortic root enlargement, supra-annular stented prosthetic valves, stentless bioprosthesis, and sutureless bioprostheses have been proposed [3].
Various procedures have been described for enlarging aortic root which includes both anterior and posterior approach. Konno procedure (aortoventriculoinfundibuloplasty) is an established procedure for enlarging aortic root by anterior approach. Patients with larger body surface area (BSA) will require higher flow rates across the valve (cardiac output) than those with a smaller BSA.
Knowledge of the patient's BSA and the effective orifice area (EOA) of prosthesis give an idea about the minimum valve size needed. Patient-specific factors such as age and activity level can be considered for calculating cardiac output demand; young people with active work profile will require larger prosthesis for a higher cardiac demand [4].
Since implanting an undersized valve or not intervening on small aortic root can worsen outcome due to increased preload, Konno procedure is extremely useful. Hence, we performed this study to review the cases in which Konno procedure was done.

Patient Characteristics
Between 2011 and 2019, 12 patients underwent Konno procedure along with aortic valve replacement with mechanical aortic valve prostheses were performed in our hospital (Table 1). Of these 12 patients, 11 underwent aortic valve replacement alone and one patient underwent mitral valve replacement along with aortic valve replacement. Among them, 3 were females, and 9 were males,  Table 1. Symptoms at admission included dyspnoea with angina in 2 patients, angina in 10 patients, and no patient had history of syncope or arrythmia. Mean preoperative New York Heart Association (NYHA) class was 2.6. Since all patients were of age less than 40 years, coronary angiography was not done as coronary artery disease was rare in this age group. Aetiology for aortic stenosis was bicuspid aortic valve alone in 3 patients, bicuspid aortic valve with calcification in 1 patient and rheumatic aetiology in 8 patients, all patients gave informed consent to publication of their data. Preoperative evaluation included hemogram, kidney and liver function tests, chest radiographs, electrocardiogram and echocardiography. A complete M-mode, two-dimensional, and Doppler evaluation was performed. LV ejection fraction, aortic annulus diameter and aortic valve morphology were noted. The peak and mean gradients across the aortic valve as well as across the prostheses were calculated according to the modified Bernoulli equation. Mean aortic annulus size was 1.89 cm, while the peak gradient (mean in mmHg) was 87.75 and mean gradient (mean in mmHg) 55.5. Echocardiographic evaluation was repeated before discharge. Symptom profile was evaluated at follow up.

Procedure
Approach for all patients was by standard median sternotomy. to the edges of the septal incision with interrupted pledgeted mattress sutures ( Figure 1). Bileaflet mechanical valves were used for insertion in all patients. It was ensured that the size of the valve was appropriate according to body surface area avoiding patient prosthesis mismatch. Anteriorly, the valve sutures were passed through the pericardial patch ( Figure 2). The superior portion of the patch was used to close the ascending aorta. The right ventricular free wall was augmented with pericardial patch (Figure 3). Deairing was done, and the aortic   clamp was removed. After weaning from cardiopulmonary bypass with inotropic support, left ventricular vent was removed and bicaval decannulation was done. Cardioplegia cannula was removed. Reversal of heparin was done with prota-mine. Aortic cannula was removed, pacing wire and mediastinal drains were inserted. After haemostasis was achieved, incision was closed in layers. 10.75 mmHg. Indexed effective orifice area (effective orifice area/body surface area) was 1.11 (mean in cm 2 /m 2 ). There was no mortality in these 12 patients and no reoperation was needed in the follow up period. All patients were started on anticoagulation therapy, low molecular weight heparin and oral

Discussion
The term "prosthesis patient mismatch" as coined in 1978 by Rahimtoola is used to describe that stenosis of a valve may not be relieved by a prosthesis [1]. This is evident by laws of physics as Poiseuille's law states inverse relationship between resistance and fourth power of radius. Increase in diameter of prosthesis gives benefit of increased effective orifice area. Implanting a valve with larger diameter Kulik et al. showed that for patients with small aortic roots, aortic root enlargement at the time of Aortic valve replacement is a safe procedure that reduces postoperative gradients and the incidence of prosthesis-patient mismatch, but this procedure does not appreciably improve long-term clinical outcomes.
However, the procedure was associated with better freedom from late congestive heart failure [7]. In an analysis done by Rodolfo V. Rocha et al., aortic root en-largement was not associated with increased risk of mortality or adverse events.
They suggested aortic root enlargement is safe adjunct to aortic valve replacement [8]. Konno procedure is a well documented in the past. Our study demonstrates that the procedure is associated with a significant decline in LVOTO gradient, stabilization of left ventricular function, and improvement in functional class. In our series, all patients undergoing Konno procedure with aortic valve replacement had good post-operative outcomes in terms of mean gradient and no mortality. Also, all the patients had symptoms in NYHA class I in the post-operative period. The limitation of our study is that there is no long-term follow-up data. However, based on our experience, Konno procedure is a safe technique and we encourage using this procedure to avoid mismatch.

Conclusion
In our study, we find Konno procedure as an effective and safe method to enlarge aortic root. Implanting a larger size prosthesis avoids patient prosthesis mismatch and leads to improved symptom profile on follow up.